👀 Views: 73 💬 Answers: 1 📅 Created: 2025-06-10

java spring-boot jackson Java

I tried several approaches but none seem to work... After trying multiple solutions online, I still can't figure this out... I'm migrating some code and I've searched everywhere and can't find a clear answer. After trying multiple solutions online, I still can't figure this out. I'm encountering an issue when trying to serialize a `LocalDateTime` object to JSON using Jackson in my Spring Boot application. Despite configuring a custom serializer, the output JSON is not formatted as expected. Here’s what I’ve done so far: I have a model class that looks like this: ```java import com.fasterxml.jackson.databind.annotation.JsonSerialize; import java.time.LocalDateTime; public class Event { private String name; @JsonSerialize(using = CustomLocalDateTimeSerializer.class) private LocalDateTime eventDate; // Getters and Setters } ``` And my custom serializer is defined as follows: ```java import com.fasterxml.jackson.core.JsonGenerator; import com.fasterxml.jackson.databind.SerializerProvider; import com.fasterxml.jackson.databind.JsonSerializer; import java.io.IOException; import java.time.LocalDateTime; import java.time.format.DateTimeFormatter; public class CustomLocalDateTimeSerializer extends JsonSerializer<LocalDateTime> { @Override public void serialize(LocalDateTime value, JsonGenerator gen, SerializerProvider serializers) throws IOException { DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSS'"); gen.writeString(value.format(formatter)); } } ``` When I serialize an `Event` object like this: ```java Event event = new Event(); event.setName("Conference"); event.setEventDate(LocalDateTime.now()); ObjectMapper objectMapper = new ObjectMapper(); String jsonString = objectMapper.writeValueAsString(event); System.out.println(jsonString); ``` I expect the date to be formatted as `2023-10-09T14:30:00.000`, but I receive an error instead: `com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class java.time.LocalDateTime`. I've checked that I've included the necessary Jackson dependencies for Java 8 time handling. Here’s my `pom.xml` snippet for dependencies: ```xml <dependency> <groupId>com.fasterxml.jackson.datatype</groupId> <artifactId>jackson-datatype-jsr310</artifactId> <version>2.12.3</version> </dependency> ``` I also registered the Java Time module like this in my configuration class: ```java import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; @Configuration public class JacksonConfig { @Bean public ObjectMapper objectMapper() { ObjectMapper mapper = new ObjectMapper(); mapper.registerModule(new JavaTimeModule()); return mapper; } } ``` I've verified that the `JavaTimeModule` is indeed registered, but I still encounter the serialization error. What am I missing? Is there something I need to adjust in the serializer or configuration? My development environment is Ubuntu. What's the best practice here? I'm developing on Debian with Java. Hoping someone can shed some light on this. The project is a CLI tool built with Java. The project is a desktop app built with Java. Could this be a known issue? The project is a service built with Java. Cheers for any assistance! I'm working with Java in a Docker container on CentOS. Is there a better approach? I'm on Debian using the latest version of Java. Thanks for taking the time to read this!